1. Field of the Invention
The present invention relates to a backing plate for sputtering preferably used in a sputtering apparatus of a magnetron sputtering system or the like used in fabricating, for example, a liquid crystal panel.
2. Description of the Related Art
For example, as shown in FIG. 7A and FIG. 7B, there is used a backing plate 51 a surface of which is attached with a target Txe2x80x2 of an ITO (Indium Tin Oxide) sintered body or the like in a magnetron sputtering system. As shown in FIG. 8, the backing plate 51 is provided with a cooling medium flow path 54 at an inner portion thereof for cooling the target Txe2x80x2 attached to the surface. Further, a rear face side of the backing plate 51 is arranged with a magnet, not illustrated, for applying a magnetic field on sputtering particles.
The conventional backing plate 51 comprises a clad plate integrally attached with two sheets of metal plates 52 and 53. As shown in FIG. 8, grooves 54a and 54b for forming the cooling medium flow path are respectively formed at an overlap face 55 for overlapping the two metal plates 52 and 53 and the two metal plates 52 and 53 are made to overlap and integrally bonded by welding (weld portions W1xe2x80x2, W2xe2x80x2) by which the cooling medium low path 54 in a circuit shape is formed at the inner portion. Further, a cooling medium (not illustrated) injected before welding the two metal plates 52 and 53 is sealed in the cooling medium flow path 54 of the backing plate 51.
Meanwhile, as mentioned above, the cooling medium flow path 54 of the conventional backing plate 51 is constituted by the grooves 54a and 54b for forming the cooling medium flow path and these grooves 54a and 54b have conventionally been formed by pressing the overlap faces 55 of the respective metal plates 52 and 53 by forming dies having forming projections in correspondence with the grooves.
However, according to the above-described conventional backing plate 51, in order to form the grooves 54a and 54b for forming the cooling medium flow path, expensive forming dies must be used and therefore, there is a drawback in which the fabrication cost is increased. Particularly, although the grooves 54a and 54b for forming the cooling medium flow path are preferably formed in a complicated circuit shape to promote the cooling efficiency, in this case, there are used forming dies having complicated forming projections in correspondence with the circuit shape of the grooves 54a and 54b and accordingly, the fabrication cost is further increased.
Further, according to the above-described conventional backing plate 51, in order to prevent the cooling medium sealed in the cooling medium flow path 54 from oozing to the overlap face 55 and leaking to outside, substantially total peripheries of peripheral edges of the two metal plates 52 and 53 must be welded without fail (weld portion W1xe2x80x2) and therefore, the welding operation becomes troublesome. The welding operation must firmly be carried out such that the weld portion W1xe2x80x2 becomes liquidtight when the cooling medium comprises a liquid and the weld portion W1xe2x80x2 becomes airtight when the cooling medium comprises a gas and therefore, the welding operation becomes further troublesome. There also poses a problem in which when a weld defect such as a nonwelded portion is present in the weld portion W1xe2x80x2, the cooling medium leaks out from the weld defect portion and accordingly, the atmosphere in the apparatus is contaminated and excellent film forming condition cannot be established. Further, although it is conceivable to attach together the two metal plates 52 and 53 by using fastening members of rivets or the like, in this case, there is a concern of leaking the cooling medium from portions of the overlap face among contiguous fastening portions, which is insufficient in achieving prevention of leakage of the cooling medium.
Further, according to the conventional backing plate 51, two sheets of the metal plates 52 and 53 need to strictly position such that corresponding ones of the grooves 54a and 54b are aligned. Accordingly, in welding them, there is separately needed a fixing device for preventing a positional shift between the two metal plates 52 and 53 and therefore, the fabrication cost is increased also in this respect and the welding operation becomes troublesome.
The invention has been carried out in order to resolve such difficulties and it is an object of the invention to provide a backing plate for sputtering which can be fabricated simply.
It is another object of the invention to provide a backing plate for sputtering having high thermal conductivity.
It is another object of the invention to provide a backing plate for sputtering which is light-weighted.
Other object of the invention will become apparent by embodiments shown below.
In order to achieve the above-described object, according to an aspect of the invention, there is provided a backing plate for sputtering, wherein a cooling portion made of a metal in a plate-like shape having a cooling medium flow path at an inner portion thereof is attached together to a base portion made of a metal in a plate-like shape.
According to the invention, as means for attaching the cooling portion to the base portion, for example, welding or a fastening member is used. As welding, for example, welding utilizing a high energy density heat source such as laser welding, electron beam welding or the like or friction agitation bonding is used. Meanwhile, as a fastening member, for example, rivet, screw, bolt, nut or clamp is used.
Further, according to the backing plate for sputtering of the invention, the cooling medium flow path is formed at the inner portion of the cooling portion and accordingly, when the cooling portion is attached to the base portion by welding with the purpose of preventing leakage of cooling medium, a substantially total periphery of a peripheral edge of the cooling portion may not necessarily be welded, accordingly, the welding operation is facilitated, in carrying out the welding, there is no need of carrying out the welding operation such that a weld portion becomes liquidtight or airtight and therefore, the welding operation is further facilitated. Further, even when a weld defect is accidentally present in a weld portion, there is no leakage of cooling medium from the weld defect portion and accordingly, the atmosphere in the apparatus is not contaminated and accordingly, excellent film forming conditions can be maintained firmly. Further, when the cooling portion is welded to the base portion, both may not be positioned each other strictly and accordingly, there is no need of necessarily using a fixing device for preventing a positional shift therebetween and accordingly, the welding operation is further facilitated. Meanwhile, even when the cooling portion is attached to the base portion by a fastening member, there poses no problem of leakage of cooling medium. Therefore, as attaching means, not only welding but also a fastening member can be used.
Further, it is preferable in the backing plate according to the above-described invention that the base portion is made of aluminum or its alloy.
Thereby, light weight formation of the backing plate can be achieved.
Further, it is preferable in the backing plate according to the above-described invention that the base portion is made of copper or its alloy.
Thereby, thermal conductivity of the base portion of the backing plate can be made high by which cooling function of the backing plate is promoted.
Further, according to the backing plate of the invention, it is preferable that the cooling portion is made of aluminum or its alloy.
Thereby, light weight formation of the backing plate can be achieved.
Further, according to the backing plate of the invention, it is preferable that the cooling portion is made of copper or its alloy.
Thereby, the thermal conductivity of the cooling portion of the backing plate can be made high by which the cooling function of the backing plate is promoted.
Further, according to the backing plate of the invention, it is preferable that the cooling portion is constituted by a roll bond panel.
Thereby, there is no need of using expensive forming dies for forming a cooling medium flow path and accordingly, even when a cooling medium flow path having a complicated circuit mode is formed, the cooling medium flow path can be formed without resulting in an increase in the cost, complicated formation of the circuit mode of the cooling medium flow path can simply be achieved by which the cooling function of the backing plate is promoted.
Further, according to the backing plate of the invention, it is preferable that the cooling portion is constituted by a roll bond panel made of aluminum or its alloy.
Thereby, light weight formation of the backing plate can be achieved, further, complicated formation of the circuit mode of the cooling medium flow path can simply be achieved by which the cooling function of the backing plate is promoted.
Further, according to the backing plate of the invention, it is preferable that the cooling portion is constituted by a roll bond panel made of copper or its alloy.
Thereby, the thermal conductivity of the cooling portion of the backing plate can be made high, complicated formation of the cooling mode of the cooling medium flow path can simply be achieved by which the cooling function of the backing plate is promoted.
Further, according to the backing plate of the invention, it is preferable that the base portion and the cooling portion are made of the same kind of metal and attached together by friction agitation bonding.
Friction agitation bonding is a kind of solid-phase bonding and therefore, there are achieved advantages in which not only metals of the same kind can solidly be bonded but also metals of different kinds can solidly be bonded, further, occurrence of thermal strain or warping in welding operation can be prevented. Therefore, by using the friction agitation bonding as attaching means, occurrence of thermal strain or warping can be prevented and a degree of close contact between a target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that the base portion and the cooling portion are made of different kinds of metals, from each other and are attached together by the friction agitation bonding.
Thereby, even when the base portion and the cooling portion are made of different kinds of metals from each other, by using the friction agitation bonding as attaching means, the base portion and the cooling portion can solidly be attached together, occurrence of thermal strain or warping can be prevented and accordingly, the degree of close contact between the target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that either of the base portion and the cooling portion is made of aluminum or its alloy and other thereof is made of copper or its alloy and the base portion and the cooling portion are attached together by the friction agitation bonding.
Thereby, light weight formation and high thermal conductivity formation of the backing plate can be achieved. Further, the base portion and the cooling portion can solidly be attached together, occurrence of thermal strain or warping can be prevented and accordingly, the degree of close contact between the target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that the base portion is made of copper or its alloy, the cooling portion is constituted by a roll bond panel made of aluminum or its alloy and the base portion and the cooling portion are attached together by the friction agitation bonding.
Thereby, light weight formation and high thermal conductivity formation of the backing plate can be achieved and complicated formation of a circuit mode of the cooling medium flow path can simply be achieved. Further, the base portion and the cooling portion can solidly be attached together, occurrence of thermal strain or warping can be prevented and accordingly, the degree of close contact between the target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that the base portion is made of aluminum or its alloy, the cooling portion is constituted by a roll bond panel made of copper or its alloy and the base portion and the cooling portion are attached together by the friction agitation bonding.
Thereby, light weight formation and high thermal conductivity formation of the backing plate can be achieved and complicated formation of a circuit mode of the cooling medium flow path can simply be achieved. Further, the base portion and the cooling portion can solidly be attached together, occurrence of thermal strain or warping can be prevented and accordingly, the degree of close contact between the target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that the base portion is made of aluminum or its alloy, the cooling portion is constituted by a roll bond panel made of aluminum or its alloy and the base and the cooling portion are attached together by the friction agitation bonding.
Thereby, light weight formation of the backing plate can be achieved and complicated formation of the circuit mode of the cooling medium flow path can simply be achieved. Further, the base portion and the cooling portion can solidly be attached together, occurrence of thermal strain or warping can be prevented and accordingly, the degree of close contact between the target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that the base portion is made of copper or its alloy, the cooling portion is constituted by a roll bond panel made of copper or its alloy and the base portion and the cooling portion are attached together by the friction agitation bonding.
Thereby, high thermal conductivity formation of the backing plate can be achieved and complicated formation of the circuit mode of the cooling medium flow path can simply be achieved. Further, the base portion and the cooling portion can solidly be attached together, occurrence of thermal strain or warping can be prevented and therefore, the degree of close contact between the target and the base portion is improved.
Further, according to the backing plate of the invention, it is preferable that the base portion and the cooling portion are made of the same kind of metal and attached together by welding utilizing a high energy density heat source.